Yield monitoring apparatus, systems and methods

ABSTRACT

A method of determining a mass flow rate, volumetric flow and test weight of grain during harvesting operations. A sensor is disposed in the harvesting machine against which clean grain piles are thrown by the clean grain elevator flights. The sensor changes the direction of the clean grain pile such that each clean grain pile compresses into a substantially discrete, contiguous shape producing discrete grain forces resulting in discrete signal pulse magnitudes generated by the sensor. The mass flow rate is calculated by summing the signal magnitudes and dividing the summed magnitudes by the sampling period. The volumetric flow rate is calculated by multiplying the pulse width generated by the sensor by a multiplier which relates pulse width to volumetric flow. The test weight of the clean grain is calculated by dividing the mass flow rate by the volumetric flow rate.

BACKGROUND

Live or real-time yield monitoring during crop harvesting is known inthe art. One type of commercially available yield monitor uses animpact-type mass flow sensor such as that disclosed in U.S. Pat. No.5,343,761, which is hereby incorporated herein in its entirety byreference. Although such monitors are generally capable of indicatingthe relative rate of mass flow in the combine during harvesting, theyare known to be substantially inaccurate. As the interest and marketinvestment in site-specific farming practices (e.g., variable rateplanting and crop input applications) has increased, the need foraccurate yield measurements (e.g., to generate accurate spatial yieldmaps by associating yield measurements with GPS-tracked locations) hasbecome more significant.

As such, there is a need for apparatus, systems and methods ofaccurately measuring mass flow rate of grain while harvesting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of a conventional combine.

FIG. 2 illustrates a conventional clean grain elevator with aconventional impact-type yield paddle.

FIG. 3 is an enlarged view of the upper portion of the clean grainelevator of FIG. 2 illustrating preferred planes for removing a portionof the clean elevator housing and tapping holes in the elevator housingfor installation of a yield sensor assembly.

FIG. 4A illustrates the same portion of the clean grain elevator of FIG.3 with one embodiment of the yield sensor assembly installed.

FIG. 4B illustrates the grain as it is being thrown from the elevatorflights against the yield sensor assembly of FIG. 4A.

FIG. 5 is a top perspective view of the yield sensor assembly embodimentof FIG. 4A.

FIG. 6 is a bottom perspective view of the yield sensor assembly of FIG.5.

FIG. 7A is a front elevation view the yield sensor assembly of FIG. 5.

FIG. 7B is a rear elevation view of the yield sensor assembly of FIG. 5.

FIG. 8A is a top view of the yield sensor assembly of FIG. 5.

FIG. 8B is a bottom view of the yield sensor assembly of FIG. 5.

FIG. 9A is an enlarged partial top view of the yield sensor assembly ofFIG. 5.

FIG. 9B is an enlarged partial bottom view of the yield sensor assemblyof FIG. 5.

FIG. 10 is a partial cross-sectional view the yield sensor assembly asviewed along lines 10-10 of FIG. 8B.

FIG. 11 is a partial cross-sectional view of the yield sensor assemblyas viewed along lines 11-11 of FIG. 8A.

FIG. 12 is enlarged partial view of the circled areas in FIG. 11.

FIG. 13 is a cross-sectional view of the yield sensor assembly alonglines 13-13 of FIG. 8A.

FIG. 14A is an enlarged view of the circled area of FIG. 13,illustrating deflection of the sensor plate.

FIG. 14B is an enlarged view of the circled area of FIG. 14A.

FIG. 15 schematically illustrates a yield monitoring system.

FIG. 16 illustrates an embodiment of a process for manufacturing theyield sensor housing of FIG. 5.

FIG. 17 illustrates an embodiment of a process for installing the yieldsensor assembly of FIG. 5 to a clean grain elevator housing.

FIG. 18 is a rear cutaway view of a clean grain elevator housingincorporating an embodiment of the grain height sensor.

FIG. 19 illustrates an embodiment of a process for generating a yieldmap.

FIG. 20 illustrates an embodiment of a process for calibrating a yieldsensor using a grain height sensor signal.

FIG. 21 illustrates a side elevation view of an upper portion of a cleangrain elevator with another embodiment of a yield sensor assembly.

FIG. 22A illustrates a side elevation view of a clean grain elevatorwith a side view of still another embodiment of a yield sensor assembly.

FIG. 22B is an enlarged side view of the yield sensor assembly of FIG.22A.

FIG. 22C is another side view of the yield sensor assembly of FIG. 22Aillustrating velocity profiles of grain within a clean grain elevatorhousing.

FIG. 23 is a graph of a yield sensor signal.

FIG. 24 illustrates a process for determining the mass flow rate,volumetric flow rate, and test weight of grain.

DESCRIPTION Conventional Combine and Yield Sensor

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views, FIG. 1illustrates a conventional combine 300. In operation, as the operator incab 312 drives the combine 300 through the field, the crop beingharvested is drawn through the head 315 into the feeder house 316 wherethe grain is separated from the other harvested plant material. Theseparated grain is lifted by a clean grain elevator 30 before beingdischarged into a collection area 318. Grain is then lifted from thecollection area 318 by a fountain auger 350 and is discharged into astorage container incorporated in the combine such as a grain tank 320.The grain is subsequently conveyed by a cross-auger 322 to an unloadingauger 330, which discharges the grain into a grain cart, wagon, truck orother vehicle for transporting for further processing or storage.

FIG. 2 schematically illustrates the clean grain elevator 30 within theelevator housing 20 of the combine 300. The elevator 30 is driven aboutan upper sprocket 35-1 and a lower sprocket 35-2. The elevator 30includes flights 32 which collect grain from a lower area generallyindicated by reference numeral 14. The flights 32 carry the grain up theheight of the elevator 30. As the flights 32 rotate past upper sprocket35-1, the grain is thrown toward the impact-type paddle 40 mountedwithin the elevator housing 20 in the area designated generally byreference numeral 16. The grain impacts the surface of the paddle 40before falling into the collection area 318. The paddle 40 is generallyinstrumented (e.g., with strain gauges) to provide a signal related tothe impact force of the grain. This signal is then transmitted to ayield monitor for processing where the impact force is correlated to themass of the grain which is displayed to the operator, typically inbushels per acre.

Yield Sensor Apparatus, Manufacture and Installation

FIG. 5 is a perspective view of an embodiment of a yield sensor assembly100, described in greater detail later. Turning to FIGS. 3 and 4A, theyield sensor assembly 100 is preferably installed at or near the top endof the clean grain elevator by removing a section of the elevatorhousing 20. As best illustrated in FIG. 3, a plane Pv runs through thecenter C of the upper sprocket 35-1 and through the center of the lowersprocket 35-2 (FIG. 2). The yield sensor assembly 100 includes arearward attachment lip 140 extending rearward of a plane P1. Therearward attachment lip 140 preferably includes holes 149 (FIG. 5)aligned along a plane A for receiving screws 142. The yield sensorassembly 100 includes a forward attachment lip 150 extending forward ofplane P2. The forward attachment lip 150 preferably includes holes 159(FIG. 5) aligned along a plane B for receiving screws 152. Bosses 162are preferably disposed below each hole in the forward attachment lip150. The attachment lips 140,150 are further illustrated in FIGS. 7A and7B, which illustrate the yield sensor assembly 100 from the front andrear, respectively.

FIG. 17 illustrates a process designated generally by reference numeral1700 for installing the yield sensor assembly 100. At step 1710, theoperator preferably cuts an opening in the elevator housing 20 (e.g.,using an acetylene torch) extending between two planes P2 and P1 (FIG.3) extending through the elevator housing forward and rearward,respectively, of the plane Pv. The opening preferably has a width (intothe page on the view of FIG. 3) sized to receive the yield sensorassembly 100. The operator then removes the portion 22 (FIG. 3) of thehousing 20 within the opening. At step 1720, the operator preferablylowers the yield sensor assembly 100 into the opening. At step 1730, theoperator preferably guides the screws 152 through the holes in theforward attachment lip 150. The screws 152 are preferably self-tapping.At step 1740, the operator preferably drives the screws 152 into theelevator housing 20, thus securing forward attachment lip to 150 theelevator housing. At step 1750, the operator preferably guides thescrews 142 through the holes in the rearward attachment lip 140. Thescrews 142 are also preferably self-tapping. At step 1760 the operatorpreferably drives the screws 142 into the elevator housing 20, thussecuring rearward attachment lip 140 to the elevator housing. It shouldbe appreciated that the steps of process 1700 may be accomplished fromoutside the elevator housing 20, such that the operator is not requiredto disassemble the elevator housing to install the yield sensor assembly100.

It should be appreciated that installation of the yield sensor assembly100 may be performed by modified processes. For example, otherembodiments of the elevator housing 20 are preferably manufactured withan opening for receiving the yield sensor assembly 100 such that cuttingan opening in the elevator housing is unnecessary.

Turning to FIG. 5, the yield sensor assembly 100 is illustrated from atop perspective view. The yield sensor assembly 100 includes a sensorhousing 110. The yield sensor assembly 100 preferably includes left andright sensors 200-1, 200-2, respectively. A lid (not shown) ispreferably removably mounted to the sensor housing 110 at an upper endthereof for protection of the sensors 200. The sensors 200 are mountedto the sensor housing 110. The sensors 200 are mounted at a forward endto a sensor plate 120. Referring to FIG. 6, which illustrates a bottomperspective view of the yield sensor assembly 100, the sensor plate 120has a sensor surface 122. The sensor surface 122 is disposed between apre-sensor surface 112 and a post-sensor surface 132. The pre-sensorsurface 112 and the post-sensor surface 132 comprise lower surfaces ofthe sensor housing 110. Referring to FIG. 8B, a width Ws of the sensorsurface 122 is preferably approximately half the width of the elevatorflights 32.

Referring to FIG. 13, the surfaces 112, 122, 132 are preferablyconcentric about the center C of the upper sprocket 35-1. The surfaces112, 122, 132 preferably have equal radii of curvature. Planes P and Qintersect the center of the upper sprocket 35-1 and a forward end 121and a rearward end 123 (FIG. 14A), respectively, of the sensor surface122. Plane P is preferably approximately co-planar with the elevatorplane Pv (FIG. 3) such that a forward end 121 (FIG. 14A) of the sensorsurface 122 is located proximate the elevator plane Pv. Elevator planePv preferably intersects the sensor surface 122. Planes P and Q definean angle A. The angle A is preferably small enough that both the forwardend 121 and the rearward end 123 of the surface 122 are proximate theelevator plane Pv. The angle A is preferably smaller than the maximumradial measurement (measured about point C) of each contiguous grainpile 50 sliding along the sensor surface 122 (e.g., grain pile 50-4 inFIG. 4B) at operational flow rates (e.g., at a grain mass flow rate of25 kilograms per second). The angle A is preferably 15 degrees.

Continuing to refer to FIG. 13, the surface 112 extends rearwardly to atransition plane 148 which is abutted to the elevator housing 20. Itshould be appreciated that the transition plane 148 is the location atwhich any grain that has been thrown from the flights 32 against theinside of the elevator housing 20 will experience a transition betweencontacting the inside of the elevator housing and contacting thepre-sensor surface 112. It should further be appreciated that the flowof grain against the surfaces may experience a disturbance if the grainencounters a gap between the transition plane 148 and the elevatorhousing 20 or if the pre-sensor surface 112 is not co-planar with theinterior surface of the elevator housing. It should further beappreciated that such a disturbance is then progressively reduced as thegrain continues to flow against the surface 112. Plane O represents anangular position counter-clockwise from which any such disturbance willbe sufficiently reduced prior to plane P such that the disturbance hasno significant impact on the signal generated by the sensors 200. PlaneN represents a plane counterclockwise from which grain is not thrownagainst the interior surface of the elevator housing 20 (or thepre-sensor surface 112) at expected flow rates. The transition plane 148is preferably counter-clockwise of plane O. The transition plane 148 ispreferably counter-clockwise of plane N. The transition plane 148 ispreferably counter-clockwise of plane O. The transition plane 148 ispreferably 45 degrees counter-clockwise of the rearward end 123 (FIG.14A) of the sensor surface 122.

FIG. 16 illustrates a process designated generally by reference numeral1600 for manufacturing the sensor housing 110 and the sensor plate 120.At step 1610, the sensor housing 110 and sensor plate 120 are preferablymade of ductile cast iron as an integral casting. At step 1620, thelower surface of the integral casting is preferably treated to improvethe material properties of the surface exposed to grain flow inoperation. For example, a thermal spraying process such as tungstencarbide high velocity oxy-fuel (HVOF) coating is preferably applied toimprove the resistance of the lower surface to wear resulting from grainflow. At step 1630, the sensor plate 120 is cut from the sensor housing110. It should be appreciated in light of the instant disclosure thatcasting and treating the sensor plate 120 together with the sensorhousing 110 results in similar wear properties of the surfaces 112, 122,132 (FIG. 6).

Referring to FIGS. 8A and 8B, the yield sensor assembly 100 isillustrated from top and bottom views, respectively. Turning to FIGS. 9Aand 9B, the yield sensor assembly is likewise illustrated from top andbottom views, respectively, and enlarged to better illustrate a smallgap 126 preferably disposed between the sensor plate 120 and the sensorhousing 110. The gap 126 is preferably smaller than the minimum width ofgrain to be harvested (e.g. smaller than 5 hundredths of an inch) withthe combine 300 such that grain is substantially excluded from enteringthe gap 126. Additionally, the gap 126 is preferably sealed with anelastic gel (not shown) such as a dielectric tough gel available fromDow Corning in Midland, Mich.

Sensor Apparatus

The sensors 200 are illustrated in detail in FIGS. 10-12. Referring toFIGS. 10 and 11, each sensor 200 preferably includes a board holder 210mounted to the sensor housing 110. A printed circuit board 230 ispreferably mounted to the board holder 210. The printed circuit board230 preferably includes a Hall-effect sensor 232 in electricalcommunication with processing circuitry for receiving a signal from theHall-effect sensor. In other embodiments, the Hall-effect sensor 232 isreplaced with other types of displacement sensors as are known in theart. An upper spring 212 is preferably mounted at a rearward end to theboard holder 210. A lower spring 214 is preferably mounted at a rearwardend to the board holder 210. The upper spring 212 is preferably mountedat a forward end to an upper magnet holder 222. The lower spring 214 ispreferably mounted at a forward end to a lower magnet holder 224. Thespring 212 and the spring 214 are preferably substantially parallel. Itshould be appreciated that the springs 212, 214 comprise a parallelsupport arm arrangement for supporting the sensor plate 120. The springs212 of each sensor 200 are preferably substantially co-planar. Likewise,the springs 214 of each sensor 200 are preferably substantiallyco-planar. An upper magnet 242 is preferably mounted to the upper magnetholder 222. A lower magnet 244 is preferably mounted to the lower magnetholder 224. As best illustrated in FIG. 11, the springs 212, 214 and theboard holder 210 are preferably mounted to the sensor housing 110 byscrews threaded into the sensor housing. The springs 212, 214 and themagnet holders 222, 224 are preferably mounted to the sensor plate 120by screws threaded into the sensor plate.

As illustrated in FIG. 12, the magnets 242, 244 have like poles 252,254, respectively, which preferably face each other. The magnets 242,244 preferably have substantially equivalent size and strength such thatthe magnetic field is approximately zero along a plane Pm equidistantfrom the magnets 242, 244. The plane Pm preferably intersects theHall-effect sensor 232 when the sensor plate 120 is not being deflectedupward by grain flow.

Operation

In operation, as best illustrated in FIG. 4B, the clean grain elevator30 collects individual grain piles 50 near a lower end and throws thegrain piles forward. As the grain piles 50 travel around the top of theconveyor, they travel radially outward from the upper sprocket 35-1 andslide along yield sensor assembly 100.

FIG. 4B further illustrates the approximate shape of the grain piles 50at several stages as the grain piles are carried around the upper end ofthe elevator 30. Grain piles 50-1 and 50-2 rest on the flights 32. Grainpile 50-3 has begun to travel around the top of the elevator 30 and hasbeen partially deformed in a radially outward fashion by centrifugalacceleration.

In a region clockwise from plane Pv, grain piles such as grain pile 50-4have been further deformed and translated such that they have beenreleased from the flight 32 and slide along the yield sensor assembly100. Thus the forward end 121 (FIG. 14A) of sensor surface 122 ispreferably located proximate elevator plane Pv.

In a region angularly clockwise from a plane R intersecting the center Cof the sprocket 35-1, grain pile 50-5 begins to lose its contiguousshape as the grain is scattered. Thus (as best seen in FIG. 13) theplane Q denoting the forward end 121 (FIG. 14A) of the sensor surface122 is preferably counterclockwise of the plane R such that the grainpassing along the sensor surface 122 has a contiguous shape.

It should be appreciated that the flow of grain across surfaces 112,122, 132 exerts radially outward forces against those surfaces. Thesurfaces 112,132 are substantially undeflected by these forces. However,as best illustrated in FIG. 14A, which is an enlarged view of thecircled area of FIGS. 13, and 14B, which is an enlarged view of thecircled area of FIG. 14A, surface 122 is deflected slightly upward by adistance D from an undeflected position (indicated by reference numeral122-1) and its deflected position. It should also be appreciated thatthe deflection of surface 122 results from translation of the entiresensor plate 120, because the sensor plate preferably comprises a solidsteel casting, the surface 122 is sufficiently tough and hard that thesurface 122 itself is not substantially deformed by contact with passinggrain. Moreover, due to the parallel arrangement of 212, 214, thedeflection of surface 122 is preferably substantially by simpletranslation (i.e., substantially without rotation) such that each pointalong the surface 122 is deflected upward by substantially the samedistance. The maximum deflection D of the paddle (i.e., the deflectionat maximum grain flow rate) is preferably less than 10 hundredths of aninch. The maximum deflection D of the paddle is preferably less than 10thousandths of an inch. The maximum deflection D of the paddle ispreferably approximately 5 thousandths of an inch. It should beappreciated that the illustrated deflection D is exaggerated in FIGS.14A and 14B for illustrative purposes. Additionally, the undeflectedposition of the forward end 121 of surface 122 is preferably higher thana rearward end of the surface 112 by a very small distance (e.g., lessthan 10 thousandths of an inch) to ensure that grain does not encountera horizontal surface when moving from the rearward end of the surface112 to the sensor surface 122. Similarly, as illustrated in FIG. 14A,the fully deflected position of the rearward end 123 of surface 122 ispreferably lower than the forward end of the surface 132 by a very smalldistance (e.g., less than 10 thousandths of an inch) to ensure thatgrain does not encounter a horizontal surface when moving from therearward end 123 of the surface 122 to the sensor surface 132 even whenthe surface 122 is fully deflected upward. It should be appreciated thatthe position of surface 132 relative to surface 122 is exaggerated inFIG. 14A for illustrative purposes.

Due to the preferably small size of gap 126 (FIG. 11), the preferablysmall upward offset of surface 122 relative to surface 112 in bothdeflected and undeflected positions of the surface 122 (FIG. 14A), thepreferably small deflection of the surface 122 in operation, and thepreferably common curvature of surfaces 112 and 122 (best seen in FIG.13), the surfaces 112 and 122 preferably comprise a nearly continuoussurface and preferably allow substantially continuous grain flow acrossboth surfaces during operation. Similarly, due to the preferably smallsize of gap 126 (FIG. 11), the preferably small upward offset of surface132 relative to surface 122 in both deflected and undeflected positionsof the surface 122 (FIG. 14A), the preferably small deflection of thesurface 122 in operation, and the preferably common curvature ofsurfaces 122 and 132 (best seen in FIG. 13), the surfaces 122 and 132preferably comprise a nearly continuous surface and preferably allowsubstantially continuous grain flow across both surfaces duringoperation. Thus it should be appreciated that the surfaces 112, 122 and132 preferably comprise a nearly continuous surface and preferably allowsubstantially continuous grain flow across all three surfaces duringoperation.

Turning to FIG. 11, the upward deflection D is allowed by deformation ofthe springs 212,214 of the sensors 200. In order to permit only a verysmall maximum deflection D of the surface 122, the effective spring rateof the springs 212, 214 is preferably approximately 20 pounds per twothousandths of an inch. The natural frequency of the yield sensorassembly 100 is preferably greater than ten times the maximum frequencyat which grain piles 50 contact the sensor surface 112. The naturalfrequency of the yield sensor assembly 100 is preferably approximately400 hertz.

Returning to FIG. 12, as the sensor plate 120 is deflected upward, themagnets 242, 244 deflect upward such that the Hall-effect sensor 232 isexposed to a stronger magnetic field. Thus as the deflection of thesensor plate 120 increases, a signal generated by the Hall-effect sensor232 increases. It should be appreciated that because the plane Pmrepresenting zero magnetic field (as discussed elsewhere herein withrespect to FIG. 12) intersects the Hall-effect sensor 232 in theundeflected state, the signal generated by the Hall-effect sensor 232changes from near-zero to a non-zero value upon deflection of the sensorplate 120. This results in more clearly delineated pulses in the signal,making the signal more conducive to processing.

Yield Measurement Systems

A yield measurement system 400 is schematically illustrated in FIG. 15with respect to the combine 300. The yield measurement system 400preferably includes a yield sensor assembly 100. As discussed elsewhereherein, the yield sensor assembly 100 is preferably mounted to the cleangrain elevator housing above the clean grain elevator. The yieldmeasurement system 400 preferably further includes a grain height sensor410, a moisture sensor 420, a global positioning receiver 430, agraphical user interface 440, and a processing board 450.

The grain height sensor 410 preferably comprises a sensor configured anddisposed to measure the height of grain being lifted by the clean grainelevator. The grain height sensor 410 is preferably mounted to the sidesof the clean grain elevator housing 20 adjacent the location where grainpiles 50 are lifted vertically before reaching the top of the cleangrain elevator 30. The grain height sensor is preferably disposed belowthe center C of upper sprocket 35-1 such that the measured grain piles50 have not been deformed by turning of the flights 32 about the uppersprocket 35-1. In an embodiment as illustrated in FIG. 18, the grainheight sensor 410 preferably comprises an optical transmitter 412configured to emit a beam 416 toward a receiver 414 disposed oppositethe passing grain piles 50. The receiver 414 is preferably in electricalcommunication with the processing board 450. In some embodiments, thegrain height sensor 410 may comprise a commercially available grainheight sensor such as that used in the 8000 i Yield Monitor availablefrom Loup Electronics in Lincoln, Nebr. It should be appreciated thatthe grain height sensor 410 is not required for operation of the yieldmonitoring system 400 or the yield sensor assembly 410.

The moisture sensor 420 preferably comprises a sensor disposed tomeasure the moisture of grain being lifted by the clean grain elevator30. For example, in some embodiments, the moisture sensor 420 comprisesa capacitive moisture sensor such as that disclosed in U.S. Pat. No.6,285,198, the disclosure of which is incorporated by reference hereinin its entirety. The moisture sensor 420 is preferably mounted to theside of the clean grain elevator housing 20 adjacent the location wheregrain piles 50 are lifted vertically before reaching the top of theclean grain elevator 30. The moisture sensor 420 is preferably inelectrical communication with the processing board 450.

The global positioning receiver 430 preferably comprises a receiverconfigured to receive a signal from the global positioning system (GPS)or similar geographical referencing system. The global positioningreceiver 430 is preferably mounted to the top of the combine 300. Theglobal positioning receiver 430 is preferably in electricalcommunication with the processing board 450.

The processing board 450 preferably comprises a central processing unit(CPU) and a memory for processing and storing signals from the systemcomponents 410, 420, 100, 430 and transmitting data to the graphicaluser interface 440.

The graphical user interface 440 preferably comprises a centralprocessing unit (CPU), a memory and interactive display interfaceoperable to display yield measurements and yield maps to the operatorand to accept instructions and data from the operator. The graphicaluser interface 440 is preferably mounted inside the cab 312 of thecombine 300. The graphical user interface 440 is preferably inelectrical communication with the processing board 450.

Yield Mapping Methods

FIG. 19 illustrates a method designated generally by reference numeral1900 for generating a yield map using the yield monitoring system 400.At step 1910, the yield sensor assembly 100 generates a yield monitorsignal which is preferably recorded and time-stamped by the yieldmonitor board 450. At step 1915, the global positioning receiver 430 (ora speed sensor such as an axle-mounted Hall-effect speed sensor as isknown in the art) preferably reports the harvesting speed of the combine300 to the yield monitor board 450, which preferably records andtime-stamps the speed data. At step 1920, the yield monitor board 450preferably calculates the local yield by, e.g., calculating the massflow rate of grain and deriving the local yield from the mass flow rateof grain using, e.g., the speed of the combine 300 and the width of thehead 315. At step 1930, the global positioning receiver 430 preferablyreports the position data (e.g., global positioning coordinates)corresponding to the position of the combine 300 to the yield monitorboard 450, which preferably records and timestamps the position data. Atstep 1940, the moisture sensor 420 preferably reports the current grainmoisture to the yield monitor board 450, which preferably calculates acorrected local yield based on the grain moisture. At step 1945, theyield monitor board 420 preferably associates recorded positions withcorrected local yields recorded at corresponding times. At step 1950,the yield monitor board 450 preferably reports the local yield andcorresponding location to the graphical user interface 440 and thegraphical user interface 440 generates a map including a graphicaldepiction of the corrected local yield at the location.

Yield Monitor Calibration Methods

FIG. 20 illustrates a process designated generally by reference numeral2000 for calibrating a yield sensor with the grain height sensor 410. Atstep 2010, the grain height sensor 410 generates a signal related to theamount of grain on the flights 32, which signal is preferably recordedby the yield monitor board 450. In other embodiments, step 2010 iscarried out using another sensor configured to measure the amount ofgrain being processed by the combine 300. At step 2020, the yield sensorassembly 100 generates a yield monitor signal related to the force ofgrain against a sensing surface, which signal is preferably recorded bythe yield monitor board 450. In some embodiments, step 2020 is carriedout using a yield sensor assembly such as yield sensor assembly 100. Inother embodiments, step 2020 is carried out using an impact-type yieldsensor paddle (e.g., the impact-type yield paddle 40 illustrated in FIG.2). At step 2030, the yield monitor board 450 preferably applies a timeshift to either the yield monitor signal or the grain height signalcorresponding to the time between the grain height sensor and yieldsensor assembly measurements. At step 2040, the yield monitor board 450preferably compares a characteristic of the yield sensor signal to thesame characteristic of the grain height signal (e.g., by comparing thesum of the yield sensor signal to the sum of the grain height signalover corresponding periods). At step 2050, the yield monitor board 450preferably determines a correction factor based on the comparison (e.g.,by dividing the sum of the grain height signal by the sum of the yieldsensor signal over corresponding periods). At step 2060, the yieldmonitor board 450 preferably applies the correction factor to the yieldsensor signal (e.g., by multiplying the correction factor by the yieldsensor signal) and reports the corrected yield sensor signal to thegraphical user interface 440.

Test Weight and Volumetric Flow Rate Measurement Methods

The yield measurement systems disclosed herein are preferably configuredto determine the volumetric flow rate of grain through the clean grainelevator 30 based on the signal generated by the yield sensor duringharvesting operations.

Turning to FIG. 23, a representative graph 2300 illustrates a signal2310 generated by the yield sensor as grain piles 50 impact the sensorsurface. A base voltage Vb represents the signal emitted when no graincontacts the sensor surface. The average value of the signal over timeis represented by average voltage Vave. A period Tp of the signal may bemeasured by measuring the time delay between the first crossings ofaverage voltage Vave. A pulse width Pw of the signal may be measured bymeasuring the time delay between the first and second crossings of theaverage voltage Vave. It should be appreciated in light of the instantdisclosure that because the grain piles on each flight is compressedinto a substantially discrete, contiguous shape against the yieldsensor, the signal 2310 includes discrete pulses having measurable pulsewidth Pw. The pulse width Pw is related to the volumetric flow rate ofgrain.

Turning to FIG. 24, a process 2400 for determining mass flow rate,volumetric flow rate, and test weight of grain is illustrated. At step2405, grain is compressed into a discrete shape (e.g., as illustrated inFIG. 4B) by changing its direction along a surface (e.g., the innersurface the housing 20 and the sensor surface 122). At step 2410, thestep of step 2405 is repeated at discrete, spaced intervals. At step2415, the grain force on the surface is measured over a sampling period,resulting in a signal such as signal 2310 in FIG. 23. At step 2417, theoperational speed of the conveyor 30 is preferably determined either bya separate sensor such as a shaft encoder, or by calculating it based onthe period Tp of the signal, which is inversely related to conveyorspeed. At step 2420, the grain forces are integrated or summed over thesampling period by multiplying the sum of voltage V by an empiricalconstant k1 relating voltage to mass flow rate. At step 2425, the massflow rate {dot over (m)} of the grain is determined by dividing the sumof grain forces over the sampling period by the duration T of thesampling period, e.g., using the relation:

$\overset{.}{m} = \frac{{\sum{k_{1}V}} + k_{2}}{T_{p}}$

-   -   Where: k2 is an empirical offset.

At step 2427, the mass flow rate measurement obtained in step 2425 ispreferably corrected by comparing the conveyor speed to a referencespeed and applying a correction factor related to said comparison. Atstep 2430, the grain mass flow rate is preferably displayed on thegraphical user interface 440. At step 2435, the pulse width Pw of thesignal is preferably measured. At step 2440, volumetric flow rate {dotover (V)} is preferably calculated based on the pulse width Pw, e.g.,using the following relation:

{dot over (V)}=k ₃(P _(w) −k ₄)

-   -   Where: k3 and k4 are an empirical multiplier and offset,        respectively.

At step 2445, a test weight of the grain is preferably determined bydividing the mass flow rate of grain by the volumetric flow rate andperforming any additional mathematical operations necessary to arrive ata standardized test weight. It should be appreciated that the standardtest weight (e.g., of corn) is the weight in pounds of a bushel (1.244cubic feet) of crop. At step 2450, the test weight is preferablydisplayed to the operator on the monitor.

Alternative Yield Sensor Embodiments

FIG. 21 illustrates an alternative yield sensor 2195. The yield sensor2195 includes a deformable sheet 2110 having a fixed end mounted to thehousing 20 above the apex of the elevator 30 and a free end disposeddownstream of the fixed end along the direction of grain travel. Thedeformable sheet 2110 is provided with instrumentation 2120 (e.g.,strain gauges or a pressure transducer) in electrical communication witha yield monitor. The instrumentation 2120 is preferably mounted on anupper side of the sheet 2110. In operation, successive grain layers passalong the surface of the deformable sheet 2110 such that the free end ofthe deformable sheet is deflected upward by centrifugal forces impartedto the grain by the elevator 30.

FIG. 22A illustrates another alternative yield sensor 2200 located in apreferred location above the apex of the elevator 30. Turning to FIG.22B, the yield sensor 2200 includes a mounting bracket 2220 mounted toan upper side of the housing 20. The yield sensor 2200 includes a sensorbody 2210 extending through an aperture in the mounting bracket 2220 andthrough an aperture provided in housing 12 such that a sensor face 2250of the sensor body 2210 is at least partially aligned with an innersurface of the housing 20. The sensor surface 2250 preferably descendsalong the direction of grain travel. The sensor surface 2250 ispreferably arcuate. In some embodiments, the sensor surface 2250 has acurvature substantially equal to that of the inner surface of thehousing 20 at a location adjacent to the sensor surface 130 (to the leftalong the view of FIG. 22B).

Continuing to refer to FIG. 22B, the sensor body 2210 includes an upperportion 2218 coupled to a stationary tower 116 by upper and lowerdisplacement arms 2214,2212. Lower displacement arm 2212 is preferably athin sheet of metal (e.g., having a thickness between 0.01 inches and0.02 inches) and is mounted at a first end to stationary tower 116 andmounted at a second to the upper portion 2218 of the sensor body 110.Upper displacement arm 2214 is preferably thicker than lowerdisplacement arm 2212. Upper and lower strain gauges 2230-1,2230-2 arepreferably mounted to upper and lower surfaces, respectively, of theupper displacement arm 2214. Strain gauges 2230-1,2230-2 are preferablyin electrical communication with a graphical user interface located inthe combine cab. Stationary tower 116 is mounted to mounting bracket2220. In operation, sequential layers of grain pass across the sensorsurface 2250, displacing the sensor body 2210 upward and imposing strainon strain gauges 2230-1,2230-2 such that a signal generated by thestrain gauges is related to the upward translation of the sensor body.

Turning to FIG. 22C, velocity profiles 2272 of cross-sections of grainpiles 50 vary between several zones 2270. In zone 2270-1, the grainvelocity is substantially uniform and substantially vertical. In zone2270-2, the magnitude of grain velocity, as well as the relativemagnitude of the vertical component of grain velocity, increases withdistance from the conveyor 20. In zone 2270-3, the magnitude of grainvelocity still increases with distance from conveyor 20, but grainwithin the zone 2270-3 preferably has a velocity substantially parallelto the sensor surface. In zone 2270-4, the velocity of the grain isinconsistent in both magnitude and direction. The sensor surface 2250 ofthe yield sensor 2200 is preferably disposed to contact grain in zone2270-3. It should be appreciated that in operation of the yield sensor100 disclosed earlier herein, grain contacts the sensor surface 122 inzone 2270-3 such that the velocity of grain immediately prior to contactwith the sensor surface 122 is substantially parallel to the sensorsurface; the velocity of the grain pile 50 is also preferablysubstantially parallel to the sensor surface 122 while in a portion ofthe grain pile is in contact with the sensor surface. Thus the forceimposed by grain contacting the sensor surface in the yield sensor 100and the yield sensor 2200 is preferably comprised substantially ofcentrifugal force rather than impact force.

The foregoing description is presented to enable one of ordinary skillin the art to make and use the invention and is provided in the contextof a patent application and its requirements. Various modifications tothe preferred embodiment of the apparatus, and the general principlesand features of the system and methods described herein will be readilyapparent to those of skill in the art. Thus, the present invention isnot to be limited to the embodiments of the apparatus, system andmethods described above and illustrated in the drawing figures, but isto be accorded the widest scope consistent with the spirit and scope ofthe appended claims.

1. A method of determining a mass flow rate during harvesting operationswith a harvesting machine, the harvesting machine having a clean grainelevator with spaced elevator flights, each of the clean grain elevatorflights carrying a clean grain pile, as each of the spaced elevatorflights passes around an upper sprocket, the clean grain pile carried byeach of the spaced elevator flights is thrown toward a sensor such thatthe clean grain pile impacts a surface of the sensor, the methodcomprising: changing a direction of each clean grain pile as each cleangrain pile passes along the surface of the sensor such that each cleangrain pile compresses into a substantially discrete, contiguous shapeagainst the surface of the sensor, whereby the changing of the directionof each clean grain pile produces a discrete grain force acting on thesensor surface, the sensor generating a discrete signal pulse having amagnitude, wherein the magnitude of the signal pulse corresponds to thediscrete grain force; recording the magnitude of each signal pulse overa sampling period duration; determining a sampling period magnitude bysumming the recorded magnitude of each discrete signal pulse generatedover the sampling period duration; determining a mass flow rate bydividing the sampling period magnitude by the sampling period duration.2. The method of claim 1, wherein the magnitude of the signal pulse is avoltage magnitude.
 3. The method of claim 1, further including:displaying the mass flow rate on a display screen visible to an operatorof the harvesting machine.
 4. The method of claim 1, wherein the step ofdetermining the sampling period magnitude includes: multiplying therecorded magnitude of each discrete signal pulse by a constant, whereinthe constant is an empirical constant relating grain mass to themagnitude of the signal pulse generated by the sensor.
 5. The method ofclaim 4, wherein the step of determining the mass flow rate includesapplying a correction factor based on a speed of the elevator flightsrelative to a reference speed.
 6. The method of claim 5, wherein thespeed of the elevator flights is determined by an encoder measuringrotation of the upper sprocket or a shaft to which the upper sprocket isrotationally fixed.
 7. The method of claim 5, wherein the speed of theelevator flights is determined by calculating a period between thesignal pulses generated by the sensor.
 8. The method of claim 1, furthercomprising: measuring and recording a pulse width of each discretegenerated signal pulse; calculating a volumetric flow rate of the cleangrain by multiplying the recorded pulse width by an empiricalmultiplier, wherein the empirical multiplier relates the pulse width tovolumetric flow.
 9. The method of claim 8, wherein the step of measuringthe pulse width includes: measuring a time delay between the signalpulse magnitudes crossing a base signal magnitude corresponding to anoutput magnitude of the sensor when no grain is impacting the surface ofthe sensor.
 10. A method of claim 8, further comprising: calculating atest weight of the clean grain by dividing the mass flow rate by thevolumetric flow rate and converting the calculated test weight to astandardized test weight; displaying the calculated standardized testweight of the clean grain on a display screen visible to an operator ofthe harvesting machine.
 11. The method of claim 10, wherein thestandardized test weight is displayed in pounds per bushel.